Drying kinetics and activation energy for solar drying of ginger slices: Solar drying of ginger

Drying is one of the oldest and most important preservation method for food in which by reducing the water activity the shelf life can be increased. In the present investigation, fresh ginger was pretreated in calcium oxide solution at different concentrations. Solar drying at three temperature levels viz., 55, 65 and 75o C at loading densities of 0.147 g/cm2, 0.176 g/cm2, 0.206 g/cm2 respectively were used for the investigation. Results of study revealed that the total time required for ginger drying in solar dryer curtails with rise in drying air temperature and increased as loading density increased. The activation energy was observed to be 20.45 kJ mol-1, 29.06 kJ mol-1 and 17.6 kJ mol-1 for 0.147 g/cm2, 0.176 g/cm2 and 0.206 g/cm2 loading density respectively. Also, the diffusivity increased with increase in temperature from 45 to 65 oC